Mirror vs. Lens

[m25]

What are the benefits of using mirrors over lens in telescope, besides the fact that mirror is not subjected to chromatic aberration?
Chromatic aberration occurs in lens because lens can refract while mirrors don't, and I was wondering if diffraction also only occurs in lens, making mirror a better choice? Or is diffraction not even relevant in terms of telescope?

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[amy_k]

Do you mean refraction rather than diffraction?

 

[m25]

Do you mean refraction rather than diffraction?

No I mean diffraction. I know that refraction only occurs in lens, and I also want to know if diffraction can also only occur in lens.

 

[amy_k]

Diffraction is relevant to telescopes, as it impairs the resolution. So the difference between mirrors and lenses in telescopes is much more significant when we are talking about powerful telescopes with high-resolution. Diffraction can be a problem using both mirrors and lenses in optics, where refraction only occurs in lenses (and everyday glass-fronted mirrors). Very powerful telescopes must therefore use large mirrors or lenses. Large mirrors are much more practical than large lenses, and since the large lens must also be designed to correct the chromatic aberration, it would be extremely expensive to use a large lens in a powerful telescope.

 

[m25]

Diffraction is relevant to telescopes, as it impairs the resolution. So the difference between mirrors and lenses in telescopes is much more significant when we are talking about powerful telescopes with high-resolution. Diffraction can be a problem using both mirrors and lenses in optics, where refraction only occurs in lenses (and everyday glass-fronted mirrors). Very powerful telescopes must therefore use large mirrors or lenses. Large mirrors are much more practical than large lenses, and since the large lens must also be designed to correct the chromatic aberration, it would be extremely expensive to use a large lens in a powerful telescope.

So diffraction occurs to the same degree as lens do?

 

[amy_k]

If they were of the same diameter, yes, but the combined effect of aberration and diffraction in lenses would cause even more of a loss in focus.